effect of stocking densities on growth and feed

American Journal of Biology and Life Sciences 2015; 3(6): 211-217

Published online October 9, 2015 (http://www.openscienceonline.com/journal/ajbls)

Effect of Stocking Densities on Growth and Feed Utilization of Hybrid Catfish (Clarias gariepinus X Heterobranchus longifilis) Fed at 1% Body Weight

Chukwuma Okereke Ofor1, Ofonime Edet Afia

2, * 1Department of Fisheries and Aquatic Resources Management, Michael Okpara University of Agriculture, Umudike, Nigeria 2Department of Fisheries and Aquatic Environmental Management, University of Uyo, Uyo, Nigeria

Email address

[email protected] (C. O. Ofor), [email protected] (O. E. Afia)

To cite this article Chukwuma Okereke Ofor, Ofonime Edet Afia. Effect of Stocking Densities on Growth and Feed Utilization of Hybrid Catfish (Clarias

Gariepinus X Heterobranchus Longifilis) Fed at 1% Body Weight. American Journal of Biology and Life Sciences.

Vol. 3, No. 6, 2015, pp. 211-217.

Abstract

The stocking density of hybrid catfish (Clarias gariepinus X Heterobranchus longifilis) fed at 1% body weight was

investigated. The fish were reared using tarpaulin tanks measuring 1m3 in 250 litres of water and was grouped into five

densities-9, 18, 38, 75 and 100 fish/m3. The experiment had three replicate and lasted for 12 months during wish monthly

sampling was done to measure body weight and feed was adjusted accordingly. The highest mean weight gain was at stocking

density 75 fish/m3 (766.60 ± 139.18) while the lowest weight gain was recorded at stocking density 100 fish/m

3 (625.16 ±

68.14) and was not significantly different (p>0.05). There was no significant difference in specific growth rate and feed

conversion ratio in all the stocking densities (p>0.05). Protein efficiency ratio of stocking density 100 fish/m3 and 75 fish/m

3

were similar (p>.05) and significantly different from others (p<0.05). The highest percentage survival of 64% was recorded at

stocking density 38 fish/m3 while the least was recorded at stocking density 100 fish/m

3. There was significant difference

among the treatments (p<0.05). Mean water quality parameters ranged from: temperature 28.3°C-28.7°C, Dissolved oxygen

5.05 mg L – 5.42 mg/L, pH 7.08 -7.69. This was within the range suitable for aquaculture. Stocking density 75 fish/m3 can be

used at 1% body weight feeding to achieve high weight gain.

Keywords

Hybrid Catfish, Stocking Density, Water Quality, Growth, Feed Utilization

1. Introduction

Stocking density is a major factor in determination of

successful aquacultural practices. With the high human

population and increased demand for fish and fish products,

it is necessary to increase stocking density of ponds to

enhance productivity. Stocking density is known as the

weight of fish per unit volume of water [1] or the number of

fish stocked at the beginning of a culture period [2]. Stocking

density has direct effect on growth and survival. In spite of

the research on stocking density, it is still difficult to obtain

information on better densities for each species, because the

best densities are affected by different culture systems, fish

species and fish age [3]-[5]. Farmers grow fish in high

stocking density in order to maximize productivity [6]. For

aquaculture to succeed, there is need for proper species

selection, adequate feeding, maintenance of water quality and

general management. Stocking density may affect fish

growth performance, physiology and fish behavior [7], [1],

influence feeding activities, metabolism distortion and

digestive utility [8], [9] feed utilization [10], hormonal

alteration [11] and immunological activities [12], [13].

Growth of fish can be influenced by availability of space,

adequate feed and other environmental factors. Fish feed

constitute a major limiting factor for large scale aquaculture

as the cost of feed is high and this reduces the profitability in

the overall production. This study therefore aimed at feeding

fish at 1% of its body weight at all the stocking densities to

reduce the cost of production and to deduce best growth

performances among the stocking densities.

212 Chukwuma Okereke Ofor and Ofonime Edet Afia: Effect of Stocking Densities on Growth and Feed Utilization of

Hybrid Catfish (Clarias gariepinus X Heterobranchus longifilis) Fed at 1% Body Weight

2. Materials and Methods

2.1. Study Area

The study was carried out at the University of Uyo, Uyo,

Akwa Ibom State, Nigeria which lies between latitudes

4°52'S and 4°51

' N and longitudes 7°54

'W and 8°03

' E. The

area is influenced by the movement of the low pressure

system as the Inter tropical Discontinuity (ITD), sometimes

referred to as the Inter tropical Convergence Zone (ITCZ).

This is a zone separating the humid maritime tropical air

mass, with its associated northwesterly winds. The area has

two distinct seasons as a result of the ITCZ, a dry season

which extends from November to March and a prolonged wet

season starting from March to October. A brief lull in the

middle of the wet season is another feature of the rainfall

pattern and is referred to as the “August break”. Mean

monthly temperatures are high and change only slightly

during the year.

Fig. 1. Map of the study area (Insert: Map of Nigeria showing the location of Akwa Ibom State) (Google earth, 2014).

The fingerlings of Heterobranchus longifilis X Clarias

gariepinus (hybrid catfish) used and was obtained from a

breeding exercise using two broodstock females and two

broodstock males. The selection of brood fish was based on

external morphology and eggs characteristics.

Fifteen tarpaulin tanks measuring 1×1×1m3

were used.

American Journal of Biology and Life Sciences 2015; 3(6): 211-217 213

Each was designed with an outlet for easy drainage.

Complete Randomized design was used for this study. The

experiment was designed to have five stocking densities and

each was fed at 1% body weight. Each treatment was

replicated three times. The initial weight of the fingerlings

was taken before stocking them in the various tanks which

were randomly positioned.

The fish was fed three times a day using commercial feed.

The feed was adjusted monthly with increase in body weight.

To calculate and monitor growth parameters, fish were

randomly weighed from each tank and measurements taken

before the start of the experiment and same was done every

month.

The biological parameters that were computed include:

2.2. Mean Weight Gain (MWG)

This was computed as the difference between initial and

final weight values of fish in each pond.

Mean Weight Gain (MWG) (%) =(W� − W�)

W�

× 100

Where Wt is weight of fish at time t, W0 is weight of fish

at time O, and t is the culture period in days

2.3. Specific Growth Rate (SGR)

This was calculated as:

Specific Growth Rate (SGR); SGR =��

×

!��

!

Where; Loge =Natural log, W1 = Final Mean Weight, W0 =

initial Mean Weight and T = Trial duration.

Nutrient utilization indices were expressed as follows;

2.4. Food Conversion Ratio (FCR)

This was computed as: FCR = $%&'(� )* *%%+

,-&�&./ 0�)12&-'

2.5. Protein Efficiency Ratio (PER)

PER = Mean Weight Gain of Fish

Protein intake

Where protein intake = total feed intake

Protein content of feed

2.6. Survival Rate (SR)

SR (%) =Number of survival

Initial stocking× 100

2.7. Water Quality Parameters

2.7.1. Temperature

This was measured monthly using a mercury in glass

thermometer calibrated 0°-50°C which was dipped in the

various tanks and read off after two minutes.

2.7.2. Hydrogen Ion Concentration (pH)

This was measured monthly using an electronic pH meter.

2.7.3. Dissolved Oxygen

This was measured monthly using dissolved oxygen meter

(HI 9146).

2.8. Statistical Analyses

Scientific Package for Social Sciences (SPSS version 19)

was used to determine the means, one way Analysis of

Variance (ANOVA), New Duncan Multiple Range Test was

used to separate the means. Microsoft Excel 2010 was used

for graphical illustrations of monthly growth parameters.

3. Results

Table 1 shows summarized growth and feed utilization

parameters of the cultured hybrid catfish. Mean Weight Gain

(MWG) was best at stocking density 75 fish/m3 (766.60 ±

139.18) and the poorest was at stocking density 100 fish /m3

(625.17 ± 68.14). There was no significant difference

(p>0.05) in the different stocking densities. The Specific

Growth Rate (SGR) showed no significant difference

(p>0.05) for the hybrid catfish grown in the different

stocking densities. The best mean Feed Conversion Ratio

(FCR) was at stocking density 100 fish/m3 while the worst

was at stocking density 9 fish/m3 although, the means were

not significantly different (p>0.05) among the treatment

tanks. Protein Efficiency Ratio (PER) was best at stocking

density 75 fish/m3 (1.897 ± 0.19) and second to that was at

stocking density 100 fish /m3 (1.881 ± 0.19). The least in

PER was at stocking density 9 fish /m3 (1.275 ± 0.19) and

was significantly different from all others. Percentage

survival was highest at stocking density 38 fish/m3 (64.0% ±

5.51), followed by stocking density 9 fish /m3. Survival at

stocking density 100 fish/m3 was significantly different

(p>0.05) from all others (37.0% ± 7.06).

Table 1. Growth and feed utilization parameters during the experiment.

9 fish/m3 18 fish /m

3 38 fish /m

3 75 fish /m

3 100 fish /m

3

Initial weight 2.07 ± 0.33 a 2.03 ± 0.88 a 2.17 ± 0.33 a 2.03 ± 0.88 a 2.00 ± 0.00 a

Final weight 740.10 ± 71.20a 658.73±82.12a 674.10 ± 83.52 a 768.63±139.15a 627.17 ± 68.1a

MWG 737.97 ± 71.29a 656.70±82.07a 671.93 ± 83.51a 766.60± 139.18a 625.17±68.14a

FCR 1.60 ± 0.20a 1.46 ± 0.05a 1.30 ± 0.11a 1.31 ± 0.16a 1.28 ± 0.14a

PER 1.27 ± 0.19a 1.66±0.06ab 1.63 ± 0.08ab 1.90 ± 0.26b 1.88 ± 0.19a

SGR 0.60 ± 0.10a 0.61±0.03a 0.67 ± 0.02a 0.71 ± 0.24a 0.73 ± 0.02a

% Survival 59 ± 10.27b 48 ± 2.00ab 64 ± 5.51b 48 ± 3.93ab 37 ± 7.05a

Means with different superscripts along the same row are significantly different p<0.05.



Figure 2 show the monthly FCR at the different stocking

densities for feeding level 1%. In January, stocking density

100 fish/m2 and stocking density 38 fish/m

2 had the highest

value (0.49) while stocking density 9 fish/m2 had the least

value (0.32). There was a decline in FCR values for

February, March and April. May, experienced increase in the

values which was thereafter maintained throughout the

experimental period.

Figure 3 show monthly SGR for the different stocking

densities at feeding level 1%. The bar chart showed an

irregular trend. There was a sharp increase in month May and

a gradual decline through to the end.

Figure 4 show the monthly Mean Weight Gain values for

the different stocking densities at feeding level 1%, feeding

level 1.5% and feeding level 2%. Stocking density 100

fish/m2 showed the highest monthly MWG while stocking

density 18 fish/m2 showed the least MWG for feeding level

1%.

Figure 5 represent the percentage survival. This showed

low survival percentages generally. Stocking density 100

fish/m2, stocking density 75 fish/m

2, stocking density 38

fish/m2, stocking density 18 fish/m

2 and stocking density 9

fish/m2 had values of 37%, 48%, 64%, 48% and 59%

respectively. Stocking density 9 fish/m2 had the highest

survival rate.

Fig. 2. Monthly variations in feed conversion ratio.

Fig. 3. Monthly variations in specific growth rate.

Fig. 4. Monthly variations in mean weight gain.


Fig. 5. Monthly variations in percentage survival.

Table 2. Water quality parameters monitored during the experiment.

9 fish /m3 18 fish /m

3 38 fish /m

3 75 fish /m

3 100 fish /m

3

Temperature (°C) 28.4 ± 0.19a 28.7 ± 0.20a 2.85 ± 0.15a 28.3 ± 0.10a 28.5 ± 0.20a

Do (mg/L) 5.05 ± 0.05a 5.13 ± 0.06a 5.20 ± 0.05a 5.21 ± 0.09a 5.42 ± 0.09b

PH 7.08 ± 0.15a 7.48 ± 0.14ab 7.69 ± 0.15b 7.62 ± 0.15b 7.59 ± 0.15b

Means with different superscripts along the same row are significantly different p<0.05.

Temperature values recorded ranged from 28.4°C - 28.7°C,

there was no significant difference (p>0.05) among the

stocking densities.

Dissolved oxygen values showed significant difference

(p>0.05) among the treatments. Stocking densities 75

fish/m3, 38 fish/m

3, 18 fish/m

3, and 9 fish/m

3 were similar

(5.21, 5.20, 5.13 and 5.03 respectively but differed

significantly (p<0.05) from stocking density 100 fish/m3

(5.42).

pH of stocking densities 100 fish/m3, 75 fish/m

3 and 38

fish/m3

were not significantly different at (p>0.05) but

significantly different from stocking density 100 fish/m3.

4. Discussion

Stocking density is one of the main factors determining

fish growth [14], [15] and the final biomass harvested [16].

The mean weight gain varied among the treatments. Stocking

density 75 fish/m3, obtained highest weight gain among the

treatments. Socking density 100 fish/m3

could have had the

reduced weight gain due to social interactions through

competition for space; this could have led to increase in

stress that resulted in increase in energy requirements causing

a reduction in weight gain. Similar observations were made

by [17]-[21]. At stocking density 75 fish/m3

which showed

higher weight gain above all others, it can be assumed that at

this density there was metabolic savings and low energy

expenditure. This findings is similar to that reported by [22]-

[24] who achieved best weight gain at lower stocking

densities. The lower densities provide more space, food and

less competition, which is reported by [25]. The greatest

improvements in SGR were found in the highest stocking

although they were not significantly different. References

[26], [27] reported similar findings which described an

increment on growth rate with the increasing of stocking

density. It is assumed that The FCR range of 1.28-1.59 was

not affected by the stocking density of fish as there was no

significant difference among the treatments. The feed

conversion ratio recorded the best values at stocking density

100 fish/m3. This indicates that stocking density did not

affect feed consumed as fish in all the treatments were fed

according to their body weight. This was not similar to the

finding of [28] Chang 1988 who stated that as the number of

fish stocked in an aquarium increases, the amount of feed

available to each fish decreases. Reference [29] stated that

the food conversion ratio ranges from 0.9 to 1.9 for turbot fed

on dry pellets. High FCR values can be attributed to various

factors like feed quality and feeding, temperature variations,

rearing units and size of fish.

The Percentage survival was least at the highest stocking

density (100 fish/m3). This could be attributed to

overcrowding which led to competition for space hence the

weaker ones were eliminated through cannibalism.

Reference [30] reported that the lower density gave larger

size and higher survival rate in Clarias macrocephalus.

Reference [31] obtained similar findings where lower

stocking density showed higher survival of Clarias

angullaris. The relations between stocking density and PER

obtained in the study were in agreement with many reports

on other catfish species.

Survival rates were inversely related to stocking density.

Reference [32] reported that the survival rate of African

catfish in ponds was not clearly influenced by stocking

density. Similarly, [33] reported that mortality of Nile tilapia

raised in cages was not dependent on stocking density.

Reference [34] reported that it is assumed that catfish, being

air-breathing species, are highly likely to be tolerant of

higher densities, therefore they are less likely to be subject to

density-dependent mortality and can easily survival if the

nutritional and environmental conditions are met. They stated

that the density-dependent mortalities may be expected

during early life stages if stocked at high densities. The mean



weight and survival rate decreased with increasing stocking

density, feed conversion ratio and specific growth rate were

not affected by stocking density.

Water quality recorded in this study agrees with the

recommendation by [35]. The parameters measured were

within the optimal range as reported by [36]-[38]

5. Conclusion

The results presented here indicate that hybrid catfish

(Clarias gariepinus X Heterobranchus longifilis) reared at

stocking density of 75 fish /m3 produced the best weight gain

and PER. The percentage survival rate was related to

stocking density as the lower stocking density showed

significantly higher rate of survival.

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